Evaluation of scanning resolution,detector choice and detector orientation to be used for accurate and time-efficient commissioning of a 6MV clinical linear accelerator

The present study is aimed at exploring different scanning parameters, detectors and their orientations for time-efficient and accurate commissioning of a 6 MV clinical linear accelerator (LINAC). Beam profiles and percentage depth dose (PDD) curves were measured with a PTW dosimetry diode, a PTW Semiflex and a PinPoint ion chamber in different orientations. To acquire beam data, equidistant (step size of 0.5 mm, 1 mm, 2 mm and 3 mm) and fanline (step size of 2–0.5 mm, 2–1 mm, 3–0.5 mm and 3-1 mm) scanning modes were employed and data measurement time was recorded. Scan time per measurement point was also varied (0.2 s, 0.5 s and 1.0 s) to investigate its effect on the accuracy and acquisition time of beam data. Accuracy of the measured data was analyzed on the basis of the variation between measured data and data modeled by a treatment planning system. Beam profiles (particularly in penumbra region) were found to be sensitive to variation in scanning resolution and showed an improved accuracy with decrease in step size, while PDD curves were affected negligibly. The accuracy of beam data obtained with the PTW dosimetry diode and the PinPoint ion chamber was higher than those obtained with the PTW Semiflex ion chamber for small fields (2?×?2 cm² and 3?×?3 cm²). However, the response of the PTW diode and the PinPoint ion chamber was significantly indifferent in these fields. Furthermore, axial orientation of the PTW Semiflex ion chamber improved accuracy of profiles and PDDs as compared to radial orientation, while such a difference was not significant for the PinPoint ion chamber. It is concluded that a scan time of 0.2 s/point with a fanline scanning resolution of 2–1 mm for beam profiles and 3 mm for PDDs are most favorable in terms of accuracy and time efficiency. For small fields (2?×?2 cm² and 3?×?3 cm²), a PinPoint ion chamber in radial orientation or a dosimetry diode in axial orientation are recommended for both beam profiles and PDDs. If a PinPoint ion chamber and a PTW dosimetry diode are not available, a Semiflex ion chamber in axial orientation may be used for small fields.

     

Effectiveness of Mechanisms and Models of Coordination between Organizations,Agencies and Bodies Providing or Financing Health Services in Humanitarian Crises: A Systematic Review

Background

Effective coordination between organizations, agencies and bodies providing or financing health services in humanitarian crises is required to ensure efficiency of services, avoid duplication, and improve equity. The objective of this review was to assess how, during and after humanitarian crises, different mechanisms and models of coordination between organizations, agencies and bodies providing or financing health services compare in terms of access to health services and health outcomes.

Methods

We registered a protocol for this review in PROSPERO International prospective register of systematic reviews under number PROSPERO2014:CRD42014009267. Eligible studies included randomized and nonrandomized designs, process evaluations and qualitative methods. We electronically searched Medline, PubMed, EMBASE, Cochrane Central Register of Controlled Trials, CINAHL, PsycINFO, and the WHO Global Health Library and websites of relevant organizations. We followed standard systematic review methodology for the selection, data abstraction, and risk of bias assessment. We assessed the quality of evidence using the GRADE approach.

Results

Of 14,309 identified citations from databases and organizations'' websites, we identified four eligible studies. Two studies used mixed-methods, one used quantitative methods, and one used qualitative methods. The available evidence suggests that information coordination between bodies providing health services in humanitarian crises settings may be effective in improving health systems inputs. There is additional evidence suggesting that management/directive coordination such as the cluster model may improve health system inputs in addition to access to health services. None of the included studies assessed coordination through common representation and framework coordination. The evidence was judged to be of very low quality.

Conclusion

This systematic review provides evidence of possible effectiveness of information coordination and management/directive coordination between organizations, agencies and bodies providing or financing health services in humanitarian crises. Our findings can inform the research agenda and highlight the need for improving conduct and reporting of research in this field.     

Botanicals for the prevention and treatment of cutaneous melanoma

Cutaneous melanoma, a cancer of melanocytes, when detected at later stages is arguably one of the most lethal cancers and the cause of more years of lost life than any other cancer among young adults. There is no standard therapy for advanced-stage melanoma and the median survival time for patients with metastatic melanoma is <1 yr. An urgent need for novel strategies against melanoma has directed research towards the development of new chemotherapeutic and biologic agents that can target the tumor by several different mechanisms. Recently, several dietary agents are being investigated for their role in the prevention and treatment of various forms of cancer and may represent the future modality of the treatment. Here, we have reviewed emerging data on botanicals that are showing promise for their potential inhibitory effect against cutaneous melanoma.     

Tolerance of Bt corn (MON 810) to maize stem borer, Chilo partellus (Lepidoptera: Pyralidae)

Transgenic corn (MON 810), expressing the Bacillus thuringiensis (Bt) protein, Cry1Ab, was evaluated under greenhouse conditions for its tolerance to the maize stem borer, Chilo partellus. Bt corn (MON 810) provided effective protection against the stem borer even under a high level of larval infestation in the greenhouse. The observed tolerance is examined and discussed in the light of the susceptibility of C. partellus to the Cry1Ab protein in laboratory bioassays. The implications of the tissue concentrations of Cry1Ab in MON 810, and baseline susceptibility recorded in the current study, for insect-resistance management are discussed.     

Intraperitoneal injection of saline modulates hippocampal brain receptor complex levels but does not impair performance in the Morris Water Maze

The involvement of the hippocampus in pain has been demonstrated but key players, i.e. the major brain receptors have not been shown to be modulated by pain. It was therefore the aim of the study to show the concerted action and pattern of brain receptor complex levels in a non-invasive model of moderate pain. C57BL/6J mice were divided into four groups of 14 animals each: trained injected, trained non-injected, yoked injected and yoked non-injected. Animals were tested in the open field and the elevated plus maze for behavioural evaluation and cognitive functions were tested using the Morris Water Maze. Hippocampi were taken 6 h following sacrification. Membrane proteins were prepared by ultracentrifugation and run on blue native gels to keep the native state, blotted to membranes and western blotting was carried out using the primary antibodies against serotonin receptor 5HT1A, muscarinic acetylcholine receptor M1 (mAChR-M1), nicotinic acetylcholine receptor alpha7 (nAChR-alpha7), glutamate (AMPA) receptor (GluR1) and neurokinin receptor 1 (NK-1). There was no difference between performance in behaviour or in the MWM between groups. Brain receptor level changes involved all receptors given above. Pain affected mAChR-M1, GluR1 and NK-1 complex levels when yoked-injected were compared with yoked non-injected animals. Memory mechanisms affected mAChR-M1 complex levels when trained non-injected animals were compared with yoked non-injected controls. Taken together, the neurochemical basis for testing receptor agonists/antagonists on the role of pain and the hippocampus was generated that may be useful for interpretations of the role of this complex area in moderate pain.     

Modafinil improves performance in the multiple T-Maze and modifies GluR1, GluR2, D2 and NR1 receptor complex levels in the C57BL/6J mouse

Modafinil has been shown to modify behavioural and cognitive functions and to effect several brain receptors. Effects, however, were not observed at the receptor protein complex level and it was therefore the aim of the study to train mice in the multiple T-Maze (MTM) as a paradigm for spatial memory and to determine paralleling brain receptor complex levels. Sixty C57BL/6J mice were used in the study and divided into four groups (trained drug injected; trained vehicle injected; yoked drug injected; yoked vehicle injected). Animals obtained training for 4?days and were killed 6?h following the last training session on day 4. Hippocampi were dissected from the brain, membrane fractions were prepared by ultracentrifugation and were run on blue-native gels and immunoblotted with antibodies against major brain receptors. Modafinil treatment led to decreased latency and increased average speed, but not to changes in pathlength and number of correct decisions in the MTM. Drug effects were modifying receptor complexes of GluR1, GluR2, D2 and NR1. Training effects on receptor complex levels were observed for GluR3, D1 and nicotinic acetylcholine receptor alpha 7 (Nic7). GluR1 levels were correlating with GluR2 and D1 levels were correlating with D2 and NR1. Involvement of the glutamatergic, NMDA, dopaminergic and nicotinergic system in modafinil and memory training were herein described for the first time. A brain receptor complex pattern was revealed showing the concerted action following modafinil treatment.     

Is Content Really King? An Objective Analysis of the Public's Response to Medical Videos on YouTube

Medical educators and patients are turning to YouTube to teach and learn about medical conditions. These videos are from authors whose credibility cannot be verified & are not peer reviewed. As a result, studies that have analyzed the educational content of YouTube have reported dismal results. These studies have been unable to exclude videos created by questionable sources and for non-educational purposes. We hypothesize that medical education YouTube videos, authored by credible sources, are of high educational value and appropriately suited to educate the public. Credible videos about cardiovascular diseases were identified using the Mayo Clinic''s Center for Social Media Health network. Content in each video was assessed by the presence/absence of 7 factors. Each video was also evaluated for understandability using the Suitability Assessment of Materials (SAM). User engagement measurements were obtained for each video. A total of 607 videos (35 hours) were analyzed. Half of all videos contained 3 educational factors: treatment, screening, or prevention. There was no difference between the number of educational factors present & any user engagement measurement (p NS). SAM scores were higher in videos whose content discussed more educational factors (p<0.0001). However, none of the user engagement measurements correlated with higher SAM scores. Videos with greater educational content are more suitable for patient education but unable to engage users more than lower quality videos. It is unclear if the notion “content is king” applies to medical videos authored by credible organizations for the purposes of patient education on YouTube.     

Kinetics and Molecular Docking Study of an Anti-diabetic Drug Glimepiride as Acetylcholinesterase Inhibitor: Implication for Alzheimer’s Disease-Diabetes Dual Therapy

Neurochemical Research - At the present time, treatment of two most common degenerative disorders of elderly population i.e., Type 2 Diabetes Mellitus (T2DM) and Alzheimer’s disease (AD) is a...     

Characterization of a Spontaneous Retinal Neovascular Mouse Model

Background

Vision loss due to vascular disease of the retina is a leading cause of blindness in the world. Retinal angiomatous proliferation (RAP) is a subgroup of neovascular age-related macular degeneration (AMD), whereby abnormal blood vessels develop in the retina leading to debilitating vision loss and eventual blindness. The novel mouse strain, neoretinal vascularization 2 (NRV2), shows spontaneous fundus changes associated with abnormal neovascularization. The purpose of this study is to characterize the induction of pathologic angiogenesis in this mouse model.

Methods

The NRV2 mice were examined from postnatal day 12 (p12) to 3 months. The phenotypic changes within the retina were evaluated by fundus photography, fluorescein angiography, optical coherence tomography, and immunohistochemical and electron microscopic analysis. The pathological neovascularization was imaged by confocal microscopy and reconstructed using three-dimensional image analysis software.

Results

We found that NRV2 mice develop multifocal retinal depigmentation in the posterior fundus. Depigmented lesions developed vascular leakage observed by fluorescein angiography. The spontaneous angiogenesis arose from the retinal vascular plexus at postnatal day (p)15 and extended toward retinal pigment epithelium (RPE). By three months of age, histological analysis revealed encapsulation of the neovascular lesion by the RPE in the photoreceptor cell layer and subretinal space.

Conclusions

The NRV2 mouse strain develops early neovascular lesions within the retina, which grow downward towards the RPE beginning at p15. This retinal neovascularization model mimics early stages of human retinal angiomatous proliferation (RAP) and will likely be a useful in elucidating targeted therapeutics for patients with ocular neovascular disease.